Third generation partnership project (3GPP) and Long Term Evolution (LTE) mobile telecommunication systems provide high data rate, lower latency and improved system performances. With the rapid development of “Internet of Things” (IOT) and other new user equipment (UE), the demand for supporting massive machine communications increases exponentially. IoT air interface will need to support both high connection density for massive IoT devices and low radio latency for reliable communication application. In addition, the network coverage is critical to connect various IoT devices in the field, and thus it is more reasonable to support the IoT communications over lower frequency bands.
In LTE, devices can obtain the UL grant through either dedicated scheduling request (SR) or random access (RA) procedure. SR allows multiple users multiplexing together with different cyclic shifts and orthogonal sequences to occupy the dedicated resource elements (REs) on the physical uplink control channel (PUCCH). At most thirty-six devices can be multiplexed together for SR in one physical resource block (PRB) on PUCCH. This method cannot meet the requirement for massive deployment of IoT or other types of machine type communication (MTC) devices. The RA process is a four-step process designed for initial cell access and UL grant request. The four-step introduces a lot of signaling overheads and delay in the set up. With the massive amount of IoT or MTC devices deployed, the regular RA process becomes inefficient. It also creates increasing number of collisions, which in turn aggravate the inefficiency of bandwidth use and system performance.
Improvements and enhancements are needed for the LTE random access procedure and the LTE SR procedure.